Flame spray coating is commonly used to apply wear-resistant coatings to steel parts. Such parts may be first heated to a temperature such as 2100.degree. F., which is a large portion of the typical melting temperature of steel such as 2700.degree. F., the heating being followed by flame spraying or plasma flame spraying. A long thin workpiece such as a piston rod of a high pressure mud pump for oil well drilling, may be coated by holding it on a lathe and rotating it while a heat gun slowly passes along it. When the rod is sufficiently heated, a flame spray gun is slowly passed back and forth along a portion of the rod which is to be coated. When the rod has cooled it is cylindrically ground. During the heating and flame spraying, the rod may become slightly bent, so that a coated middle portion may become non-concentric with the cylindrical ends of the rod. As a result, grinding of the middle portion to a true cylindrical surface concentric with its ends, may result in the coating on one side of the rod being ground much thinner than the coating on the other side. For example, a hollow rod or pipe of three inches diameter and 50 inches length may be bent so its coated middle is displaced 25 mil (one mil equals one thousandth inch). After grinding the coated cylindrical surface true with the rest of the rod, the coating will be of unequal thickness, being perhaps 100 mil thick on one side and 50 mil thick on the other due to the 25 mil bending of the rod. Since the lifetime of wear may depend upon the minimum thickness of the coating, such uneven coating would reduce the service life of the rod. To prevent this, a thicker coating has to be applied, and a longer grinding operation has to be conducted to grind the rod true. A system which minimized such unevenness, would be of considerable benefit in the flame spray coating of long thin workpieces.